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Lasers Could Give Space Research its ‘Broadband’ Moment

By Doug Messier
Parabolic Arc
February 17, 2017
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Several upcoming NASA missions will use lasers to increase data transmission from space. (Credit: NASA’s Goddard Space Flight Center/Amber Jacobson, producer)

GREENBELT, Md. (NASA PR) — Thought your Internet speeds were slow? Try being a space scientist for a day.

The vast distances involved will throttle data rates to a trickle. You’re lucky if a spacecraft can send more than a few megabits per second (Mbps) — a pittance even by dial-up standards.

But we might be on the cusp of a change. Just as going from dial-up to broadband revolutionized the Internet and made high-resolution photos and streaming video a given, NASA may be ready to undergo a similar “broadband” moment in coming years.

The key to that data revolution will be lasers. For almost 60 years, the standard way to “talk” to spacecraft has been with radio waves, which are ideal for long distances. But optical communications, in which data is beamed over laser light, can increase that rate by as much as 10 to 100 times.

High data rates will allow researchers to gather science faster, study sudden events like dust storms or spacecraft landings, and even send video from the surface of other planets. The pinpoint precision of laser communications is also well suited to the goals of NASA mission planners, who are looking to send spacecraft farther out into the solar system.

“Laser technology is ideal for boosting downlink communications from deep space,” said Abi Biswas, the supervisor of the Optical Communications Systems group at NASA’s Jet Propulsion Laboratory, Pasadena, California. “It will eventually allow for applications like giving each astronaut his or her own video feed, or sending back higher-resolution, data-rich images faster.”

Science at the speed of light

Both radio and lasers travel at the speed of light, but lasers travel in a higher-frequency bandwidth. That allows them to carry more information than radio waves, which is crucial when you’re collecting massive amounts of data and have narrow windows of time to send it back to Earth.

A good example is NASA’s Mars Reconnaissance Orbiter, which sends science data at a blazing maximum of 6 Mbps. Biswas estimated that if the orbiter used laser comms technology with a mass and power usage comparable to its current radio system, it could probably increase the maximum data rate to 250 Mbps.

That might still sound stunningly slow to Internet users. But on Earth, data is sent over far shorter distances and through infrastructure that doesn’t exist yet in space, so it travels even faster.

Increasing data rates would allow scientists to spend more of their time on analysis than on spacecraft operations.

“It’s perfect when things are happening fast and you want a dense data set,” said Dave Pieri, a JPL research scientist and volcanologist. Pieri has led past research on how laser comms could be used to study volcanic eruptions and wildfires in near real-time. “If you have a volcano exploding in front of you, you want to assess its activity level and propensity to keep erupting. The sooner you get and process that data, the better.”

That same technology could apply to erupting cryovolcanoes on icy moons around other planets. Pieri noted that compared to radio transmission of events like these, “laser comms would up the ante by an order of magnitude.”

Clouding the future of lasers

That’s not to say the technology is perfect for every scenario. Lasers are subject to more interference from clouds and other atmospheric conditions than radio waves; pointing and timing are also challenges.

Lasers also require ground infrastructure that doesn’t yet exist. NASA’s Deep Space Network, a system of antenna arrays located across the globe, is based entirely on radio technology. Ground stations would have to be developed that could receive lasers in locations where skies are reliably clear.

Radio technology won’t be going away. It works in rain or shine, and will continue to be effective for low-data uses like providing commands to spacecraft.

Next steps

Two upcoming NASA missions will help engineers understand the technical challenges involved in conducting laser communications in space. What they’ll learn will advance lasers toward becoming a common form of space communication in the future.

The Laser Communications Relay Demonstration (LCRD), led by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is due to launch in 2019. LCRD will demonstrate the relay of data using laser and radio frequency technology. It will beam laser signals almost 25,000 miles (40,000 kilometers) from a ground station in California to a satellite in geostationary orbit, then relay that signal to another ground station. JPL is developing one of the ground stations at Table Mountain in southern California. Testing laser communications in geostationary orbit, as LCRD will do, has practical applications for data transfer on Earth.

Deep Space Optical Communications (DSOC), led by JPL, is scheduled to launch in 2023 as part of an upcoming NASA Discovery mission. That mission, Psyche, will fly to a metallic asteroid, testing laser comms from a much greater distance than LCRD.

The Psyche mission has been planned to carry the DSOC laser device onboard the spacecraft. Effectively, the DSOC mission will try to hit a bullseye using a deep space laser — and because of the planet’s rotation, it will hit a moving target, as well.

8 responses to “Lasers Could Give Space Research its ‘Broadband’ Moment”

  1. Aerospike says:

    Lol 250 Mbps slow… As far as I know, even in the US there are regions that dream of such connections…

    • Michael Grigoni says:

      Where I work (in the US) we pay through the nose for 100 Mbps and are lucky to get 10 Mbps over a single tcp socket. I guess expectations are raised in areas where fiber to the home is available at affordable rates and the backhaul isn’t oversold.

    • JamesG says:

      That is true. However the real gotcha here (that the article is rather oblivious to) is the error checking and latency of deep space links. It doesn’t matter how fast or dense your link is if it takes 20 minutes, a hour or 8 hrs. for you to send a request to retransmit for random data packets that were lost.

      • Aerospike says:

        Well of course deep space communications have their own unique set of challenges and constraints.
        My point was not about how fast (or not) 250Mbps is, but that the PR actually said that 250Mbps “… might still sound stunningly slow to Internet users.”

        250Mbps is pretty much the fastest connection I can get, and I live the f…ing capital of my country (Austria). And I’m not complaining here, I currently “only” have a 75 Mbps line and I really don’t now why I would need more at the moment.

        I just found it hilarious that whoever wrote that PR thought that a 250 mbps internet connection would be considered “slow”. 😉

  2. Tom Billings says:

    The paucity of radio/microwave bandwidth for space probes is unthinkable to many on the internet. The fact is though that lasercoms will be a large part of making dwellers in Space rich, and humans always follow wealth. The reason is the very vacuum humans complain about in that environment. Lasercoms here on Earth *must* have fiber laid between connecting points to be reliable over any significant distance because of atmospheric interference. Communicating between points in Space, however, will mean basically point and shoot, and the higher the bandwidth available, ….well, …information access is wealth beyond the dreams of Croesus as the population accessed grows larger.

    On Earth, the poor must beg the rich for much, including the optical fiber to make themselves wealthy. In Space, the least wealthy will have as much bandwidth as the wealthiest. Want to talk from LEO with someone at EML-1 about a new asteroid discovery as a small investor’s investment? Point and shoot! Thus it could very well be that the larger access to amounts of knowledge JPL can only dream of today will be driving the settlement of the Solar System. Knowledge is wealth, and with lasercoms, there is nothing to stand in the way of you getting it, once you are in Space.

  3. Saturn1300 says:

    300ghz RF sounds like it can do as well as lasers.

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